//主体部分
#main{
    background: url('https://img.fishfay.com/theme/images/antacn/login/login-01.jpg') no-repeat;
    background-size: 100% 100%;
    width: 100%;
    height: 653px;
    position: relative;
}
#main #sign{
    width: 450px;
    height: 500px;
    background-color: rgba(255,255,255,0.8);
    border-radius: 20px;
    position: absolute;
    top: 70px;
    right: 40px;
    display: flex;
    flex-direction: column;
    align-items: center;
    h1{
        margin: 80px 0 60px 0;
        line-height: 0;
    }
    #form{
        width: 350px;
        input{
            border: 0;
            padding: 0 10px;
            margin-top: 20px;
            width: 330px;
            height: 50px;
            border-radius: 5px;
        }
    }
    a{
        margin-top: 30px;
        color: black;
    }
}
#main #sign #form input:nth-child(3){
    width: 350px;
    height: 60px;
    cursor: pointer;
    background-color: black;
    color: #fff;
}